Institutions and Organizations today are facing several unique communication challenges:

Transcription

1 CHAPTER 1 Introduction Institutions and Organizations today are facing several unique communication challenges: the proliferation of electronic messages across their enterprise; the need to provide employees, customers, students and partners with consistent information; the desire to better equip information workers with meaningful information to drive informed decisions; and the mandate to control costs without sacrificing application, availability, security or reliability. Various types of SMS text messages can be sent from multiple platforms, applications and devices to making it easier to connect internal and external systems and deliver robust, integrated intelligent solutions that help drive informed decisions and increase productivity across the entire organization by controlling costs without sacrificing performance, availability, or scalability. The simplicity, speed and convenience of Short Messaging Service (SMS) have helped promote its wide usage. Initially, the usage of SMS was to complement the functions of a standard mobile phone. Lately, many have started to commercialize the usage of the SMS, for instance, sending money (M-Pesa), shopping for commodities from retail stores, paying for electricity and water bills, and querying bank account balances among others. This project takes advantage of the convenience and speed of the SMS technology, so as to design and implement an application that would enable students retrieve their examination results via SMS. 1

2 1.1 Problem Statement The project aims at reducing the havoc students go through to travel long distances, queue at examination offices or crowd at notice boards to view their results. It even goes further to reduce the amount of paper work that would otherwise be involved during preparation and presentation of these results. The student is registered and student details stored in a database. The student sends as SMS with a service code to server. It validates the service code and processes the student request. An SMS notifying the student of his/her results is then ensued. 1.2 Objective Objectively, this project sets out three main purposes for its relevance. Firstly, that the success of this project will be crucial in explaining its adoption by the University of Nairobi, Department of Electrical and Electronic Engineering. Secondly, that the examination results are secure within the database that stores examination results. Lastly, that it is simple and easily understood by the end-users. For simplicity, I have split this paper into four broad sections. In the first section, I present the literature review on SMS technology. In section two, I provide a brief discussion on databases, PC-to-mobile connectivity using AT commands. The methodology of design and implementation is in section three, whereas the fourth section handles results of the experimental analysis. This report concludes by discussing the limitations faced during design and implementation and recommendations for future work. 2

3 CHAPTER 2 LITERATURE REVIEW 2.1 SMS Theory SMS stands for Short Messaging Service. A Short Messaging Service is a binary string that contains all the necessary information to form the message header needed for transportation and the message body that contains the payload. The basic addressing scheme of SMS messages are mobile telephone numbers called MSISDN. This technology enables the sending and receiving of messages between mobile phones. SMS first appeared in Europe in It was included in the GSM standards and later ported to wireless technologies like CDMA and TDMA. The GSM and SMS standards were originally developed by ETSI. ETSI is abbreviated to mean European Telecommunications Standards Institute. Now 3GPP is responsible for the development and maintenance of the GSM and SMS standards. As the name suggests Short Messaging Service, the data that can be held by an SMS is at most 140 bytes. This actually implies that one SMS message can contain up to: 160 characters if 7-bit character encoding is used. 7-bit character encoding is suitable for encoding Latin characters e.g. English alphabets. 70 characters if 16-bit Unicode UCS2 character encoding is used. This is mainly used in text messages containing non-latin characters like Chinese. 3

4 An SMS message can carry binary data. This makes it possible to send ringtones, pictures, operator logos, wallpapers, animations, business cards and WAP configurations to a mobile phone via SMS. SMS is a success all over the world. The number of SMS messages exchanged every day is enormous. SMS messaging is now one of the most important revenue sources of wireless carriers. The SMS technology presents the following merits: SMS Messages can be Sent and Read at Any Time; almost every person has a mobile phone and carries it most of the time. SMS Messages can be sent to an Offline Mobile Phone; an SMS can be sent to a mobile phone that is switched off or if the recipient of the text is in a place where the wireless signal is temporarily unavailable. SMS Messages are supported by 100% GSM mobile phones and can be exchanged between different wireless carriers. SMS supports reverse billing, which enables payment to be made conveniently. 2.2 Short Messaging Service Centre A Short Messaging Service Centre, usually abbreviated as SMSC, is responsible for handling the SMS operations of a wireless network. When an SMS message is sent from a mobile phone, it will reach an SMSC first. The SMSC then forwards the SMS message towards the destination. An SMS message may need to pass through more than one network entity (e.g. SMSC and SMS gateway) before reaching the destination. 4

5 The main duty of an SMSC is to route SMS messages and regulate the process. Figure1. Basic Network Architecture for an SMSC Figure 1 represents the basic network architecture for an SMSC deployment handling multiple input sources, including a voic system (VMS), Web-based messaging, integration, and other external short message entities (ESMEs). Communication with the wireless network elements such as the home location register (HLR) and mobile switching center (MSC) is achieved through the signal transfer point (STP). Visitor Location Register (VLR) The visitor location register is a database that contains temporary information about subscribers homed in one HLR who are roaming into another HLR. MSC The MSC performs the switching functions of the system and controls calls to and from other telephone and data systems. The MSC will deliver short message to the specific mobile subscriber through the base station. 5

6 Air Interface The air interface is defined in each one of the different wireless technologies (GSM, TDMA, and CDMA). These standards specify how the voice or data signals are transferred from the MSC to the handset and back, as well as the utilization of transmission frequencies, considering the available bandwidth and the system s capacity constraints. 2.3 SMS Gateway The SMS gateway is a relay between two SMSCs. It translates one SMSC protocol to another in order to facilitate two different wireless carriers to interconnect their SMSCs for purposes such as, enabling the exchange of inter-operator SMS messages. Any two SMSCs cannot connect if they do not support a common SMSC protocol. Figure2: An SMS gateway acts as a relay between two SMS centers 6

7 To connect to an SMS gateway, you can use an SMSC protocol such as SMPP and CIMD. Some SMS gateways support an HTTP / HTTPS interface. HTTP / HTTPS are easier to use than SMSC protocols. The drawback is that there may be fewer SMS features to use. For example, an SMS gateway may not support the sending of picture messages through the HTTP / HTTPS interface Basic services The Short Message Service comprises of two basic services: SM MT (Short Message Mobile Terminated); SM MO (Short Message Mobile Originated). SM MT denotes the capability of the GSM system to transfer a short message submitted from the SMSC to one MS, and to provide information about the delivery of the short message either by a delivery report or a failure report with a specific mechanism for later delivery. SM MO denotes the capability of the GSM system to transfer a short message submitted by the MS to one SME via an SMSC, and to provide information about the delivery of the short message either by a delivery report or a failure report. The message must include the address of that SME to which the SMSC shall eventually attempt to relay the short message. 7

8 2.3.2 Short Message Service elements Validity-Period Service-Centre-Time-Stamp Status report capabilities Validity-Period The Validity-Period parameter value indicates the time period for which the SMS is valid, i.e. how long the SMSC shall guarantee its existence in the SMSC memory before delivery to the recipient. Service-Centre-Time-Stamp The Service-Centre-Time-Stamp is the information element by which the SMSC informs the recipient about the time of arrival of the SMS. Sender: Year: Month: Day: Hour: Minute: Second: Status report capabilities The SMS also offers to the SMSC the capabilities of informing the MS of the status of a previously sent mobile originated short message. The status of the message can be: Successfully delivered to the SME; The SMSC was not able to forward the message to the SME. The reason can be an error of permanent or temporary nature. Permanent errors can be e.g. validity period expired, invalid SME address. 8

9 2.4 GSM Modem A GSM modem is a wireless modem that works with a GSM wireless network. A wireless modem behaves like a dial-up modem. The main difference between them is that a dial-up modem sends and receives data through a fixed telephone line while a wireless modem sends and receives data through radio waves. A GSM modem can be an external device or a PC Card / PCMCIA Card. Typically, an external GSM modem is connected to a computer through a serial cable or a USB cable. Like a GSM mobile phone, a GSM modem requires a SIM card from a wireless carrier in order to operate. The number of SMS messages that can be processed by a GSM modem per minute is about six to ten SMS messages per minute. 2.5 GPRS Modem A GPRS modem is a GSM modem that additionally supports the GPRS technology for data transmission. It is a packet-switched technology that is an extension of GSM whereas GSM is a circuit-switched technology. A key advantage of GPRS over GSM is that GPRS has a higher data transmission speed. If SMS over GPRS is used, then about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM that averages at approximately six. 9

10 2.6 Drawbacks of the SMS Technology One SMS message can only carry a very limited amount of data. To overcome this drawback, an extension called concatenated SMS (also known as long SMS) was developed. A concatenated SMS text message can contain more than 160 English characters. The drawback of concatenated SMS is that it is less widely supported than SMS on wireless devices. Another major drawback is an SMS message cannot include rich-media content such as pictures, animations and melodies. EMS (Enhanced Messaging Service) was developed in response to this. The drawback of EMS is that it is less widely supported than SMS on wireless devices. Also, many EMS-enabled wireless devices only support a subset of the features defined in the EMS specification. A certain EMS feature may be supported on one wireless device but not on the other. 10

11 CHAPTER 3 DATABASES A database is a collection of information, tables and other objects organized and presented to serve a specific purpose, such as facilitating searching, sorting and recombining data. Databases can either be in the form of cards, paper files or electronic. An electronic database is any collection of data that is specially and specifically organized for rapid search and retrieval by a computer. Advantages of electronic database Searching speed: electronic databases with powerful servers can be searched through a query in a couple of seconds on any millions of records. Flexibility on data level: having structures of data one can build different templates of the same data. Archive advantage: when the database is properly designed and maintained, it will still search rapid and return results fast several years down the line. Future growth advantage: with electronic databases one can easily redesign without having a reason to rewrite everything like it would in the case of a manual database. Variety of share points: an electronic database can be accessed by many users at the same time. Examples of electronic databases include; Microsoft Access, PostgreSQL, Microsoft SQL, Oracle, MySQL etc. 11

12 3.1 SQL Express SQL Express is a client/server relational database management system (RDBMS). The terms client/server are used to refer to very general concepts or specific items of hardware or software. A client is any component of a system that requests services or resources from other system components. A server is any system component that provides services or resources to other system components. An RDBMS is a collection of data organized in two-dimensional tables consisting of named columns and unique rows. Each table represents the mathematical concept of a relation as defined in set theory. In set theory columns are known as attributes and rows are known as tuples. The operations that may be performed on tables are similarly based on manipulation of relations to produce new relations, usually referred to as queries or views. Microsoft SQL server controls access to your data to ensure that multiple users can work with it concurrently, to provide fast access to it and ensure only authorized users can obtain access. Hence, SQL Express is a multi-user, multi-threaded server. 3.2 Database file types Database files are categorized into three types: Primary data file. This file is the starting point of the database. Every database must have one, but only one. Primary data filenames have an.mdf extension. 12

13 Secondary data files. These files are optional and can hold all data and objects that are not on the primary data file. A database does not have to have secondary data files, but may have secondary data files. Secondary data filenames have an.ndf extension. Log files. These files hold all the transaction log information used to recover the database. Every database has at least one log file. Log filenames have an.ldf extension. 3.3 The Design Process The best way of understanding database design is to start with an all-in-one, flat-file table design then later on tossing in sample data to examine what happens. By analyzing sample data, one will be able to identify the problems caused by the initial design. Modification of the design to eliminate the problems is therefore of primary importance. Modification and re-modification is a continual process until a consistent and problem-free design is achieved. Ultimately, the design will depend on the complexity of the data, each time the database is designed. However, the following are vital points to any design process: Break composite fields down into constituent parts. Example: name becomes lastname and firstname. Create a key field which uniquely identifies each record. 13

14 Eliminate repeating groups of fields. Example: if a table contains fields Location 1, Location 2, Location 3 containing similar data, it is a sure warning sign. Eliminate record modification, deletion and addition problems by ensuring each non-key field depends on the entire key. To achieve this, create a separate table for any information that is used in multiple records, and then use a key to link these tables to one another. SQL Express is based on the relational data model and uses SQL as its query language. The relational data models: 1. It is a model that is easily understood and visualized. 2. Reduced data redundancy. 3. Independent physical storage and logical database structures. 4. Its integrity laws are easy to develop and understand. 14

15 CHAPTER 4 MOBILE PHONE & PC CONNECTIVITY There are two widely used ways through which a mobile phone can be physically connected to a computer: Via Bluetooth Via serial data cable Commands are sent to the phone to perform certain tasks; these commands are the same regardless of the type of connection used. 4.1 AT Commands AT commands are instructions used to control a modem. AT is the abbreviation of ATtention. Since every command line starts with "AT" or "at" hence the name AT commands. Many of the commands that are used to control wired dial-up modems are also supported by GSM/GPRS modems and mobile phones. GSM/GPRS modems and mobile phones support an AT command set that is specific to the GSM technology, which includes SMS-related commands like AT+CMGS (Send SMS message), AT+CMSS (Send SMS message from storage), AT+CMGL (List SMS messages) and AT+CMGR (Read SMS messages). 15

16 4.2 Basic Commands and Extended Commands There are two types of AT commands: Basic commands Extended commands. Basic commands are AT commands that do not start with "+". For example, D (Dial), A (Answer), H (Hook control) and O (Return to online data state) are basic commands. Extended commands are AT commands that start with "+". All GSM AT commands are extended commands. For example, +CMGS (Send SMS message), +CMSS (Send SMS message from storage), +CMGL (List SMS messages) and +CMGR (Read SMS messages) are extended commands. All SMS messaging commands are extended AT commands. Some of the tasks that can be achieved using AT commands with a GSM/GPRS modem or mobile phone include: Get basic information about the mobile phone or GSM/GPRS modem. For example, name of manufacturer (AT+CGMI), IMEI number (AT+CGSN) Get basic information about the subscriber. For example, IMSI number (AT+CIMI). Get the current status of the mobile phone or GSM/GPRS modem. For example, mobile phone activity status (AT+CPAS) Establish a data connection or voice connection to a remote modem ATD (Dial), ATA (Answer). Send and receive fax (ATD, ATA, AT+F*). 16

17 Send (AT+CMGS, AT+CMSS), read (AT+CMGR, AT+CMGL), write (AT+CMGW) or delete (AT+CMGD) SMS messages and obtain notifications of newly received SMS messages (AT+CNMI). Read (AT+CPBR), write (AT+CPBW) or search (AT+CPBF) phonebook entries. Control the presentation of result codes / error messages of AT commands. For example, you can control whether to enable certain error messages (AT+CMEE) and whether error messages should be displayed in numeric format or verbose format (AT+CMEE=1 or AT+CMEE=2). Get or change the configurations of the mobile phone or GSM/GPRS modem. For example, change the GSM network (AT+COPS). Save and restore configurations of the mobile phone or GSM/GPRS modem. For example, save (AT+CSAS) and restore (AT+CRES) settings related to SMS messaging such as the SMS center address. Generally, GSM/GPRS modems designed for wireless applications have better support of AT commands than ordinary mobile phones. 17

18 CHAPTER 5 DESIGN 5.1 Software Microsoft Windows XP OS It is a series of software and graphical user interfaces produced by Microsoft. Microsoft named the operating environment Windows and its availability is guaranteed. SQL Express SQL Express has gained a strong reputation for being the database of choice for the open source community. It is free for personal use so fits my need for an inexpensive solution. If the system was to become commercial the license is reasonable compared to other database products like Oracle. Visual Basic.Net Visual Basic.Net provides a complete set of tools to simplify rapid application development. The Visual part refers to the method used to create the GUI. Rather than writing numerous lines of code to describe the location and appearance of interface elements. The Basic part refers to the BASIC (Beginners All-Purpose Symbolic Instruction Code) language. 18

19 5.2 Hardware Computer The computer will host the database for the exam results, the script to decipher the short message and the SMS Gateway. GSM Phone Nokia 6070 was my choice model because of its compatibility with the AT commands that I used to generate my application. USB Data Cable CA-52 was my data cable of choice since it is compatible with Nokia 6070 hence connection to the PC. GSM Modem This was so as to facilitate the sending and receiving of text messages. 19

20 5.3 Approach I decided to use a modular system of approach because I saw the solution could be broken into four distinct parts. The benefit of a modular system is that I can test each part individually and in future replacing the weak links in the chain. Modules of approach: Developing a user-interface application that will necessitate entry of students examination results into the database. Creating a database and that will store the students examination results, incoming and outgoing messages. Devising a way in which the GSM phone will communicate with the PC to aid in retrieval of results from the database via SMS. A message server that would facilitate sending and receiving of SMSs during run-time. Roles Since I was the sole developer and end-user I felt it was important to ask myself a few critical questions: End-user: How easy is it for one to use the system? Answer: The system will allow one to query your examination results simply by sending an SMS to a pre-defined number. 20

21 Dean or Chairman: How much will the system cost? Answer: The administration costs are minimal with the main cost being the reply SMS to students. When the student base grows and the SMS traffic increases we can take out a service contract with a mobile provider and get a direct SMSC link and lower cost per SMS for students. Thus, the only capital cost is contracting a mobile service provider that will handle the bulk of SMSs and also provide a pre-defined text prefix number. Technical Analyst: How many SMS messages can the system handle? Answer: With a good SMSC link the system can process, on average 15 text messages per second. Student: How confidential are my examination results? Answer: Every student will have a secret pin number that he/she will use to query his/her results. However, there will be a default pin number. Programmer: How will I keep the code understandable? Answer: VB.Net is already a fairly English language so it will be understandable to those working on the project even at a later date. Commenting within the code also helps in explaining part of the code. 21

22 Hardware Environment Processor: Pentium 4 Hard Disk Storage: 160 GB RAM: 512 MB GSM mobile phone used to access the GSM Network. The GSM phone functioned as a GSM modem. Software Environment OS: Windows XP Database: SQL Express Compiler Language: VB.Net 22

23 5.4 Implementation The application is divided into 3 major modules: Database Phone to PC connectivity using AT commands User interface The database stores the students details and incoming and outgoing messages. Once this is developed, phone to PC connectivity then follows. This connectivity will allow the GSM phone to communicate with the PC therefore acting as a modem. It would manage the sending and retrieval of messages. The user interface aids in entering student details into the database. 23

24 CHAPTER 6 RESULTS AND EVALUATION 6.1 RESULTS Upon successful registration of students details, the details were stored in a database. The student sends an SMS with service code to server. It is validates the service code and processes the student request. A result notification is later ensued. The valid message syntax is: PJ62 # Reg. No # PIN Number # R1 PJ 62: request of SMS-ERQS service Reg. No: student s unique registration number PIN Number: to curb against unauthorized view of one s results. R1: 1 st year results summary. R5 in the case of 5 th years and so on. The PIN Number was set at a default figure of TESTING Testing the application was mandatory so as to ensure it functions consistently and correctly. System testing makes a logical assumption that if all the parts of the system are correct then the goal will be successfully achieved. I conducted numerous tests on the application to ascertain the SMS-RQS functionality and query response. 24

25 6.3 SETBACKS While working on the SMS-ERQS some minor and major setbacks were encountered. Minor Setbacks 1. While developing the application syntax errors like missing identifiers proved to be very annoying. 2. Locating the correct driver that would facilitate my database connection could not pass my mention. 3. During run-time the cost per tested transaction was 7/= this translated to the entire testing process being shyly costly. Major Setbacks 1. Configuring the GSM modem to send and receive messages during design time was not something to write home about. 2. Another major setback was integrating all the modules together to have the application function as a whole. 3. I had to purchase a phone that offered better and simpler compatibility features to the AT commands. Nokia 6070 proved very appropriate. 25

26 CHAPTER 7 CONCLUSION SMS-ERQS has been developed to case out the problems students face whenever they want to view their results and champion for an improvement of the present system. This system is expected to prove useful. The goals expected to be achieved by this system are: Simplify the retrieval of exam results. Increasing productivity by spending less time to process the results. Avoiding errors by minimizing human interaction during the retrieval of the examination results. Flexible for further enhancement. After successfully developing the system and testing it, the results obtained were very satisfactory. The system is easy to use, secure and available round the clock. 26

27 CHAPTER 8 RECOMMENDATIONS AND FUTURE WORK The modular approach with which was used to develop this system has different modules performing their tasks. This guarantees that should there be any changes that need to be done to the system then it can be easily achieved by making the required change without necessarily affecting the remaining part of the system. This system was limited to SMS. However, the scope for future enhancement would see this application being web-based as well. This will require a server-side scripting language e.g. PHP that will execute scripts on the server where the website is located. 27

28 CHAPTER 9 BIBLIOGRAPHY 1. Wikipedia: The online English Encyclopedia 2. Microsoft developers website 3. Databases 4. How stuff works 28

29 CHAPTER 10 APPENDIX 10.1 Excerpt of Code SMS Based Data Access Imports System.Data Imports RixDataAccessUtility Imports SmsBasedExamRRS.Core Public Class ExamResultDAO Public Sub New() End Sub Sub Insert(ByVal result As ExamResult) If Not Me.IsDuplicate(result) Then Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, result.id) dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, result.studentnumber) dataaccess.addparameter("@course", DbType.String, ParameterDirection.Input, result.course) dataaccess.addparameter("@unitcode", DbType.String, ParameterDirection.Input, result.unitcode.code) dataaccess.addparameter("@state", DbType.String, ParameterDirection.Input, result.state) dataaccess.addparameter("@grade", DbType.String, ParameterDirection.Input, result.grade) cmd.commandtext = "Insert into ExamResults values(@studentnumber,@course,@unitcode,@state,@grade)" Dim i As Integer = dataaccess.executenonquery(cmd) Else Throw New Exception("Duplicate results detected!") End If End Sub Sub Update(ByVal result As ExamResult) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, result.id) dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, result.studentnumber) dataaccess.addparameter("@course", DbType.String, ParameterDirection.Input, result.course) dataaccess.addparameter("@unitcode", DbType.String, ParameterDirection.Input, result.unitcode.code) 29

30 DbType.String, ParameterDirection.Input, result.state) DbType.String, ParameterDirection.Input, result.grade) cmd.commandtext = "Update ExamResults set Course=@Course,StudentNumber=@StudentNumber,UnitCode=@UnitCode,Grade=@Grade,S tate=@state Where ID=@ID" Dim i As Integer = dataaccess.executenonquery(cmd) End Sub Sub Delete(ByVal result As ExamResult) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, result.id) cmd.commandtext = "Delete ExamResults where ID=@ID" Dim i As Integer = dataaccess.executenonquery(cmd) End Sub Function IsDuplicate(ByVal result As ExamResult) As Boolean Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, result.studentnumber) dataaccess.addparameter("@course", DbType.String, ParameterDirection.Input, result.course) dataaccess.addparameter("@unitcode", DbType.String, ParameterDirection.Input, result.unitcode.code) cmd.commandtext = "Select * From ExamResults Where StudentNumber=@StudentNumber AND Course=@Course AND UnitCode=@UnitCode" Dim reader As IDataReader = dataaccess.executereader(cmd) Return reader.read End Function Function Read() As List(Of ExamResult) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text cmd.commandtext = "Select ID From ExamResults" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim list As New List(Of ExamResult) While (reader.read) list.add(me.fetchbyid(convert.toint32(reader("id")))) End While reader.close() Return list End Function Function FetchByID(ByVal id As Integer) As ExamResult Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, id) cmd.commandtext = "Select * From ExamResults Where ID=@ID" 30

31 Dim reader As IDataReader = dataaccess.executereader(cmd) Dim examresult As New ExamResult Dim unitdao As New UnitDAO If (reader.read) Then examresult.id = Convert.ToInt32(reader("ID")) examresult.course = reader("course") examresult.studentnumber = reader("studentnumber") examresult.unitcode = unitdao.fetchbycode(reader("unitcode")) examresult.grade = Convert.ToInt32([Enum].Parse(GetType(Grades), reader("grade").tostring)) examresult.state = Convert.ToInt32([Enum].Parse(GetType(ResultState), reader("state").tostring)) End If reader.close() Return examresult End Function Function FetchByCode(ByVal code As String) As ExamResult Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@code", DbType.String, ParameterDirection.Input, code) cmd.commandtext = "Select * From ExamResults Where Code=@Code" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim examresult As New ExamResult Dim unitdao As New UnitDAO If (reader.read) Then examresult.id = Convert.ToInt32(reader("ID")) examresult.course = reader("course") examresult.studentnumber = reader("studentnumber") examresult.unitcode = unitdao.fetchbycode(reader("unitcode")) examresult.grade = Convert.ToInt32([Enum].Parse(GetType(Grades), reader("grade").tostring)) examresult.state = Convert.ToInt32([Enum].Parse(GetType(ResultState), reader("state").tostring)) End If reader.close() Return examresult End Function Function FetchByStudent_UnitCode(ByVal studentnumber As String, ByVal unitcode As String) As ExamResult 'If unitcode Is Nothing Then ' unitcode = "None" 'End If Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, studentnumber) dataaccess.addparameter("@unitcode", DbType.String, ParameterDirection.Input, unitcode) cmd.commandtext = "Select * From ExamResults Where StudentNumber=@StudentNumber AND UnitCode=@UnitCode" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim examresult As New ExamResult 31

32 Dim unitdao As New UnitDAO If (reader.read) Then examresult.id = Convert.ToInt32(reader("ID")) examresult.course = reader("course") examresult.studentnumber = reader("studentnumber") examresult.unitcode = unitdao.fetchbycode(reader("unitcode")) examresult.grade = Convert.ToInt32([Enum].Parse(GetType(Grades), reader("grade").tostring)) examresult.state = Convert.ToInt32([Enum].Parse(GetType(ResultState), reader("state").tostring)) End If reader.close() Return examresult End Function Function FetchByStudent(ByVal studentnumber As String) As List(Of ExamResult) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, studentnumber) cmd.commandtext = "Select ID From ExamResults where StudentNumber=@StudentNumber" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim list As New List(Of ExamResult) While (reader.read) list.add(me.fetchbyid(convert.toint32(reader("id")))) End While reader.close() Return list End Function Function FetchByStudent_Course(ByVal studentnumber As String, ByVal course As String) As List(Of ExamResult) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@studentnumber", DbType.String, ParameterDirection.Input, studentnumber) dataaccess.addparameter("@course", DbType.String, ParameterDirection.Input, course) cmd.commandtext = "Select ID From ExamResults where StudentNumber=@StudentNumber AND Course=@Course" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim list As New List(Of ExamResult) While (reader.read) list.add(me.fetchbyid(convert.toint32(reader("id")))) End While reader.close() Return list End Function End Class 32

33 Student Data Access Imports System.Data Imports RixDataAccessUtility Imports SmsBasedExamRRS.Core Public Class StudentDAO Public Sub New() End Sub Sub Insert(ByVal student As Student) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, student.id) dataaccess.addparameter("@firstname", DbType.String, ParameterDirection.Input, student.firstname) dataaccess.addparameter("@middlename", DbType.String, ParameterDirection.Input, student.middlename) dataaccess.addparameter("@lastname", DbType.String, ParameterDirection.Input, student.lastname) dataaccess.addparameter("@regnumber", DbType.String, ParameterDirection.Input, student.registrationnumber) dataaccess.addparameter("@password", DbType.String, ParameterDirection.Input, student.password) dataaccess.addparameter("@registeredcourse", DbType.String, ParameterDirection.Input, student.registrationnumber) cmd.commandtext = "Insert into Students values(@firstname,@middlename,@lastname,@regnumber,@password,@registeredcours e)" Dim i As Integer = dataaccess.executenonquery(cmd) If (i > 0) Then 'Dim regcoursedao As New RegisteredCourseDAO 'For Each course As RegisteredCourse In student.registeredcourse ' 'If course.isnew Then ' regcoursedao.insert(course) ' 'Else ' ' regcoursedao.update(course) ' 'End If 'Next End If End Sub Sub Update(ByVal student As Student) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, student.id) dataaccess.addparameter("@firstname", DbType.String, ParameterDirection.Input, student.firstname) dataaccess.addparameter("@middlename", DbType.String, ParameterDirection.Input, student.middlename) 33

34 DbType.String, ParameterDirection.Input, student.lastname) DbType.String, ParameterDirection.Input, student.registrationnumber) DbType.String, ParameterDirection.Input, student.password) DbType.String, ParameterDirection.Input, student.registrationnumber) cmd.commandtext = "Update Students set FirstName=@FirstName,MiddleName=@MiddleName,LastName=@LastName, " _ + "RegNumber=@RegNumber,Password=@Password,RegisteredCourse=@RegisteredCourse Where ID=@ID" Dim i As Integer = dataaccess.executenonquery(cmd) If (i > 0) Then 'Dim regcoursedao As New RegisteredCourseDAO 'For Each course As RegisteredCourse In student.registeredcourse ' If (course.isnew) Then ' regcoursedao.insert(course) ' Else ' regcoursedao.update(course) ' End If 'Next End If End Sub Sub Delete(ByVal student As Student) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, student.id) cmd.commandtext = "Delete Students Where ID=@ID" Dim i As Integer = dataaccess.executenonquery(cmd) If (i > 0) Then Dim regcoursedao As New RegisteredCourseDAO For Each course As RegisteredCourse In student.registeredcourse regcoursedao.delete(course) Next End If End Sub Function IsDuplicate(ByVal student As Student) As Boolean End Function Function Read() As List(Of Student) Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text cmd.commandtext = "Select ID From Students" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim list As New List(Of Student) While (reader.read) 34

35 list.add(me.fetchbyid(convert.toint32(reader("id")))) End While Return list End Function Function FetchByID(ByVal id As Integer) As Student Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@id", DbType.Int32, ParameterDirection.Input, id) cmd.commandtext = "Select * From Students Where ID=@ID" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim student As New Student Dim regcoursedao As New RegisteredCourseDAO If (reader.read) Then student.id = Convert.ToInt32(reader("ID")) student.firstname = reader("firstname") student.middlename = reader("middlename") student.lastname = reader("lastname") student.registrationnumber = reader("regnumber") student.password = reader("password") student.registeredcourse = regcoursedao.fetch(student.registrationnumber) End If Return student End Function Function FetchByRegistrationNumber(ByVal regnumber As String) As Student Dim dataaccess As New DataAccessUtility Dim cmd As IDbCommand = dataaccess.icommand cmd.commandtype = CommandType.Text dataaccess.addparameter("@regnumber", DbType.String, ParameterDirection.Input, regnumber) cmd.commandtext = "Select * From Students Where RegNumber=@RegNumber" Dim reader As IDataReader = dataaccess.executereader(cmd) Dim student As New Student Dim regcoursedao As New RegisteredCourseDAO If (reader.read) Then student.id = Convert.ToInt32(reader("ID")) student.firstname = reader("firstname") student.middlename = reader("middlename") student.lastname = reader("lastname") student.registrationnumber = reader("regnumber") student.password = reader("password") student.registeredcourse = regcoursedao.fetch(student.registrationnumber) End If Return student End Function End Class 35